[FastTextAutosizer] Remove comment about storing a fingerprint stack

This comment is no longer true (it may have never been either). The
fingerprint logic is fairly cheap because we cache the parent hash.

TBR=skobes
NOTRY=true

Review URL: https://codereview.chromium.org/207193002

git-svn-id: svn://svn.chromium.org/blink/trunk@169708 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/rendering/FastTextAutosizer.cpp

@@ -535,11 +535,6 @@ FastTextAutosizer::Fingerprint FastTextAutosizer::computeFingerprint(const Rende
         return 0;
 
     FingerprintSourceData data;
-
-    // FIXME: Instead of computing and caching parent fingerprints on demand,
-    // consider maintaining a fingerprint stack during the style recalc
-    // tree walk (similar to the cluster stack used during layout).
-
     if (const RenderObject* parent = parentElementRenderer(renderer))
         data.m_parentHash = getFingerprint(parent);